Joint Spring 2011 Meeting of the New England Sections of the APS and the AAPT
Volume 56, Number 2
Friday–Saturday, April 8–9, 2011;
Lowell, Massachusetts
Session A1: Welcome and Materials I
1:00 PM–3:00 PM,
Friday, April 8, 2011
UML ICC
Room: Ballroom
Chair: Daniel Wasserman, UMass Lowell
Abstract ID: BAPS.2011.NES.A1.3
Abstract: A1.00003 : Terahertz Spectroscopy of Complex Materials
2:05 PM–3:00 PM
Preview Abstract
Abstract
Author:
Richard D. Averitt
(Physics Department, Boston University)
Terahertz time-domain spectroscopy is a powerful tool to
investigate complex materials broadly defined. This includes
artificial electromagnetic composites such as metamaterials, and
correlated electron materials where the interplay between
microscopic degrees of freedom leads to phenomena such as
superconductivity or metal-insulator transitions. I will discuss
our recent results in these areas.
Metamaterials are a relatively new type of artificial composite
with electromagnetic properties that derive from their
sub-wavelength structure. The judicious combination of
metamaterials with MEMS technology enables reconfigurable
metamaterials where artificial ``atoms'' reorient within unit
cells in response to an external stimulus. This is accomplished
by fabricating planar arrays of split ring resonators on
bimaterial cantilevers designed to bend out of plane in response
to a thermal stimulus. In this way we can control the electric
and magnetic response of these metamaterials.
Vanadium dioxide (VO$_2$) exhibits a metal-insulator transition
(MIT) at a temperature (340K) that coincides with a structural
phase transition. This leads to the ``chicken and egg'' problem.
Is it the structural change or electron correlations that lead
to the MIT transition? Uniaxially strained VO$_2$ films have
been fabricated to help solve this problem. In unstrained VO$_2$
crystals the insulator to metal transition enables the electrons
move freely in three dimensions. Non-contact THz-TDS conductivity
measurements of strained samples reveal that the electrons prefer
to move in one direction. That is, strain induces a quasi
one-dimensional metallic conductivity.
These results reveal the utility of terahertz spectroscopy to
investigate complex materials and point the way towards future
studies of hybrid composites incorporating metamaterials with
quantum-based complex matter. Such multi-scale structures may
offer complementary benefits where quantum materials confer
additional functionality to artificial electromagnetic composites
or, conversely, metamaterials serve as a novel tool to facilitate
fundamental studies of the electrodynamic response of complex
quantum materials.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.NES.A1.3